Tang Jia Xin, Cabrera-Orefice Alfredo, Meisterknecht Jana, Taylor Lucie S, Monteuuis Geoffray, Stensland Maria Ekman, Szczepanek Adam, Stals Karen, Davison James, He Langping, Hopton Sila, Nyman Tuula A, Jackson Christopher B, Pyle Angela, Winter Monika, Wittig Ilka, Taylor Robert W
Mitochondrial Research Group, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
Functional Proteomics Center, Institute for Cardiovascular Physiology, Goethe University, Frankfurt am Main, Germany.
Life Sci Alliance. 2025 Jan 8;8(3). doi: 10.26508/lsa.202403013. Print 2025 Mar.
Pathogenic variants in cytochrome oxidase assembly factor 5 (COA5), a proposed complex IV (CIV) assembly factor, have been shown to cause clinical mitochondrial disease with two siblings affected by neonatal hypertrophic cardiomyopathy manifesting a rare, homozygous missense variant (NM_001008215.3: c.157G>C, p.Ala53Pro). The most striking observation in the affected individuals was an isolated impairment in the early stage of mitochondrial CIV assembly. In this study, we report an unrelated family in whom we have identified the same variant with patient-derived fibroblasts and skeletal muscle biopsies replicating an isolated CIV deficiency. A CRISPR/Cas9-edited homozygous knockout U2OS cell line with a similar biochemical profile was generated to interrogate the functional role of the human COA5 protein. Mitochondrial complexome profiling pinpointed a role of COA5 in early CIV assembly, more specifically, its involvement in the stage between MTCO1 maturation and the incorporation of MTCO2. We therefore propose that the COA5 protein plays an essential role in the biogenesis of MTCO2 and its integration into the early CIV assembly intermediate for downstream assembly of the functional holocomplex.
细胞色素氧化酶组装因子5（COA5）是一种推测的复合物IV（CIV）组装因子，其致病性变异已被证明可导致临床线粒体疾病，有两名受新生儿肥厚型心肌病影响的兄弟姐妹表现出一种罕见的纯合错义变异（NM_001008215.3: c.157G>C, p.Ala53Pro）。在受影响个体中最显著的观察结果是线粒体CIV组装早期的孤立性损伤。在本研究中，我们报告了一个无亲缘关系的家系，我们在其中通过患者来源的成纤维细胞和骨骼肌活检鉴定出相同的变异，复制了孤立的CIV缺陷。我们构建了具有相似生化特征的CRISPR/Cas9编辑的纯合敲除U2OS细胞系，以探究人类COA5蛋白的功能作用。线粒体复合物组分析确定了COA5在CIV早期组装中的作用，更具体地说，它参与了MTCO1成熟和MTCO2掺入之间的阶段。因此，我们认为COA5蛋白在MTCO2的生物合成及其整合到功能性全复合物下游组装的早期CIV组装中间体中起着至关重要的作用。
